Method and apparatus for manufacturing electronic device using device chip

ABSTRACT

[Object] To provide a method and an apparatus for manufacturing electronic devices by transferring the device chips from one substrate for producing device chips to the other substrate for a product having a large display. 
     [Means of Realizing the Object] A substrate having a plurality of device chips is brought into contact with a first drum including a selective adhesive region, the device chips are transferred by making the device chips be adhered to the selective adhesive layer of the first drum and separating at least part of the device chips from the substrate by rotating the first drum, then, the device chips on the first drum are made to be come into contact with the other substrate for the product, and the device chips are transferred to the substrate for the product by rotating the first drum. Additionally, the front-and-rear relation for the surfaces may be inversed by, after the device chips on the first drum are transferred to the second drum, transferring the device chips on the second drum to the substrate for the product.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a U.S. national phase application filed under 35U.S.C. § 371 of International Application No. PCT/JP2017/007571, filedFeb. 27, 2017, which claims priority from Japanese Patent ApplicationNo. 2016-062627, filed Mar. 25, 2016, designating the United States,which are hereby incorporated herein by reference in their entirety.

BACKGROUND Technical Field

The present invention relates methods for manufacturing electronicdevices using device chips. In particular, the present invention relatesto a method for manufacturing electronic devices by arranging aplurality of device chips whose sizes are finer than the size of theelectronic devices, and an apparatus for manufacturing the same.

Background Art

A display apparatus using light-emitting diodes (LEDs), which are lightemitting elements, includes a plurality of three-primary-color (RGB)LEDs that are arranged on a substrate for a display screen of thedisplay apparatus. The RGB LEDs constitute each pixel, each pixel emitslight according to image signals, and this enables an image to bedisplayed on the display screen as a whole.

Each pixel determines a resolution of the display screen. The higher theresolution (the finer the pixel) is, the smoother the image isreproduced. The larger the pixel elements are, the lower the displayresolution, thereby resulting to a coarse image, for a large-screendisplay apparatus.

LEDs are difficult to be manufactured directly on a substrate of thedisplay screen because of the size of the substrate and the problems inmanufacturing process influenced by the size. In one example, thedisplay apparatus is thus manufactured by transferring the LEDs, whichare manufactured on the compound semiconductor substrate, to the displayscreen substrate corresponding to each pixel.

For an active matrix type liquid crystal display apparatus with alarge-screen, Patent Document 1 discloses a method for manufacturing aliquid crystal display apparatus by preparing a plurality of thin-filmtransistor (TFT) elements on a first substrate, by transcribing(transferring as they are) the TFT elements selectively to a secondsubstrate for the liquid crystal display apparatus, and by sealing acrystal material between the second substrate and a opposing thirdsubstrate where a color filter is disposed.

Patent Document 1 also discloses a technology of removing the electronicdevice chips, such as TFT elements, manufactured on the substrate usinga plate-like relay substrate, and transferring the TFT elementstranscribed on the relay substrate to a substrate for a product.

Patent Document 2 discloses a technology of press-bonding electroniccomponents onto a printed circuit pattern one by one using a chipmounter.

RELATED ART DOCUMENTS

[Patent Document 1]: Japanese Unexamined Patent Application PublicationNo. 2009-152387

[Patent Document 2]: Japanese Unexamined Patent Application PublicationNo. H08-230367

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

When electronic device chips are separated and transferred from thefirst substrate for producing the electronic device chips to the relaysubstrate and are transferred to the second substrate for an electronicdevice product, a yield degradation caused by separation error (defectby lacking) may frequently occur, because the larger the relay substrateis, the larger difference of a separating force is used.

Although Patent Document 1 discloses a method for improving a separatingproperty, the manufacturing process is complicated and costly.Additionally, the disclosed process requires to be consistentlyincorporated into a manufacturing process of electronic device chips,and thus, the cost for developing the incorporation is increased.

Furthermore, when the electronic device chips are transferred to adevice chip substrate from a relay substrate, for a large or plate-likerelay substrate, the entire surface of the relay substrate is broughtinto contact with the device chip material substrate surface or thesubstrate for the product, and a larger pushing length is used.Consequently, the distortion caused by pushing to the relay substrate isincreased.

The deformation quantity is increased especially in the outer edgeportions of the substrates, because unlike the center portion the outeredge portion does not have any structure that suppresses being extended.Consequently, it makes difficult to suppress the deformation caused bydistortion in both center and outer edge portion, when fine device chipsare transferred.

In one example, if micro LEDs whose sizes of the electronic device chipsto be transferred are about 10×30 μm and where the chips are aligned atan interval of about 5 μm are manufactured, precise alignment of theabove-mentioned micron order is difficult over the entire relaysubstrate.

Furthermore, Patent Document 1 does not disclose a technology formanufacturing a display apparatus using a larger substrate for theproduct than the substrate where electronic device chips are prepared,and thus, a display apparatus with a large screen is difficult to bemanufactured using the above mentioned technology.

Alternatively, even if a plurality of substrates (glass substrates)where electronic device chips (TFT elements) are formed are prepared,and the electronic chips are repeatedly separated and transferred fromthe substrates (glass substrates) to a substrate for a product, theprocess significantly prolongs tact time and it also increases the costof manufacturing.

Patent Document 2 discloses a method of transferring device chips(electronic components) one by one to a board for the product using achip mounter. However, when this method is used, positioning accuracymay be differed depending on individual device chip and also the tacttime may be significantly increased. It may be thus not unrealistic toemploy this method when a large substrate is manufactured, and it mayfurthermore increase the manufacturing cost.

The conventional vacuum suction/chucking system for gripping devicechips by a pickup head for the chip mounter constrains the device chipsizes and significant design change, such as a mechanism change of thepickup head, may be required in order to transfer fine chips with hightact.

The present invention has been made in the light of the abovecircumstances, and its primary object is to provide a method and anapparatus for manufacturing electronic devices by transferring devicechips to a substrate for a product or the like at low cost and higharrangement accuracy.

Means of Solving the Problems

According to one embodiment of the present invention, a method ofmanufacturing electronic devices includes

a preparation step for preparing a first substrate having a firstadhesive layer and a second substrate having a second adhesive layer,the first adhesive layer including a surface where a plurality of devicechips are adhered,

a first take-out step for making at least part of the device chips onthe first substrate come into contact with and adhere to at least partof a selective adhesive region on a third adhesive layer of a first drumand for separating at least part of the device chips from the firstsubstrate by rotating the first drum, and

a first transfer step for making the device chips on the selectiveadhesive region come into contact with and adhere to the second adhesivelayer of the second substrate and for separating the device chips fromthe selective adhesive region by rotating the first drum.

In the embodiment of the present invention, an adhesion force betweenthe first adhesive layer and the device chips may be weaker than anadhesion force between the selective adhesive region and the devicechips, and

the adhesion force between the selective adhesive region and the devicechips may be weaker than an adhesion force between the second adhesivelayer and the device chips.

Such a use of a manufacturing method may enable a separating force forseparating the plurality of device chips from the first substrate wherethe device chips are adhered to be further reduced, and the uniformityof the separating force to be enhanced. It may improve the arrangementaccuracy of the device chips on the second substrate, may shorten thetact time for transferring the device chips, and further may surelytransfer the device chips by controlling the adhesion force.

Furthermore, the device chips do not require to be manufactured directlyon the second substrate, and thus, the second substrate is not subjectto any limitation for the process of manufacturing the device chips,such as heat resistance and chemical resistance. In addition to it,since such a limitation is not necessary, neither the second substratemay be deformed nor a positioning deviation may occur.

According to one embodiment of the present invention, a method ofmanufacturing electronic devices includes

a preparation step for preparing a first substrate having a firstadhesive layer and a second substrate having a second adhesive layer,the first adhesive layer including a surface where a plurality of devicechips are adhered,

a first take-out step for making at least part of the device chips onthe first substrate come into contact with and adhere to at least partof a selective adhesive region on a third adhesive layer of a first drumand for separating the at least part of the device chips from the firstsubstrate by rotating the first drum, and

an inversion step for making the device chips on the selective adhesiveregion of the first drum come into contact with and adhere to a fourthadhesive layer of a second drum and for separating the device chips fromthe selective adhesive region by rotating the first drum and the seconddrum oppositely to each other, and

a second transfer step for making the device chips come into contactwith and adhere to the second adhesive layer of the second substrate andfor separating the device chips from the second drum by rotating thesecond drum.

In the embodiment of the present invention, an adhesion force betweenthe first adhesive layer and the device chips may be weaker than anadhesion force between the selective adhesive region and the devicechips,

the adhesion force between the selective adhesive region and the devicechips may be weaker than an adhesion force between the fourth adhesivelayer and the device chips, and

the adhesion force between the fourth adhesive layer and the devicechips may be weaker than an adhesion force between the second adhesivelayer and the device chips.

In the embodiment of the present invention, the method of manufacturingelectronic devices may include

the preparation step for preparing the first substrate having the firstadhesive layer and the second substrate having the second adhesivelayer, the first adhesive layer including the surface where theplurality of device chips are adhered,

the first take-out step and the first transfer step, and

the first take-out step, the inversion step, and the second transferstep.

The transferring of the device chips using the first and second drumsenables the front and rear surfaces of each device chip to be invertedbetween the first and second substrates, and also enables the front andrear surfaces of each device chip to be properly and at leastselectively combined depending on connections of the device chips withother circuit or element, etc. for the product to be manufactured.

Additionally, the front and rear surfaces of each device chip may beinverted collectively and it may minimize an added time caused by thetact time for inverting.

In the embodiments of the present invention, the method of manufacturingelectronic devices may further include

the first take-out step and

a parallel-move step for separating the first drum from the firstsubstrate after the first take-out step and for moving the firstsubstrate in a direction parallel to a rotation shaft of the first drum.

The first take-out step and the parallel-move step are repeated severaltimes, so as to transfer the device chips to the selective adhesiveregion of the first drum.

The device chips may be transferred by repeating the first take-out stepand the parallel-move step and it may enable the device chips to betransferred to the intended location on the second substrate, even ifthe area of the second substrate is larger than the area of the firstsubstrate. Consequently, it may shorten the tact time for arranging thedevice chips and may also reduce the manufacturing cost.

In the embodiments of the present invention, the selective adhesiveregion may include convex portions.

The selective adhesive region of the first drum may include the convexportions, which are formed so to project from the surrounding adhesivelayer, so that the device chips are selectively adhered to thepredetermined area of the first drum. Additionally, the arrangement ofthe convex portions on the adhesive layer of the first drum may beproperly adjusted according to type of the electronic device, and it mayenable the intended number of the device chips to be adhered to theintended area with intended positional accuracy.

According to one embodiment of the present invention, an apparatus formanufacturing electronic devices includes a traveling guide, a firstconveying table, a second conveying table, and a first drum.

The first conveying table include a first traveling device that makesthe first conveying table move on the traveling guide and a traversingdevice that moves perpendicularly to the longitudinal direction,

the second conveying table includes a second traveling device that makesthe second conveying table move on the traveling guide, and

the first drum includes a first rotation shaft, a first elevating devicefor raising and lowering the first drum, a first rotation device forrotating the first drum around the first rotation shaft, and a mechanismfor controlling a tilt angle in the longitudinal and/or verticaldirections of the first rotation shaft of the first drum against thefirst conveying table, and further includes a third adhesive layerhaving a selective adhesive region.

In such an above configuration, the elevating device lowers the firstdrum until the selective adhesive region of the first drum comes intocontact with the device chips on the first adhesive layer of the firstsubstrate placed on the first conveying table,

the selective adhesive region is brought into contact with the firstsubstrate surface, and the first conveying table is moved while thefirst drum is being rotated,

the adhesion force of the selective adhesive region and the rotarymotion caused by the first rotation device allow the device chips to betaken-out from the first substrate by making the device chips at leastselectively adhere to the selective adhesive region and by separatingthe device chips from the first substrate,

subsequently, the first drum is raised, the second conveying table ismoved below the first drum, and the first elevating device of the firstdrum lowers the first drum,

the device chips on the selective adhesive region are brought intocontact with the second adhesive layer of the second substrate on thesecond conveying table, and

the taken-out device chips on the selective adhesive region can besequentially transferred to the second substrate by moving the secondconveying table while the first drum is being rotated.

Consequently, compared with the case using a flat relay substrate, theshape of the drum allows the device chips to be brought intoline-contact, not surface-contact, with the drum, and leads the reducedpushing length. Accordingly, the uniform weak force allows the devicechips to be separated from the first substrate and to be transferred tothe second substrate that is a substrate for the product, and thus, thearrangement accuracy for the device chips may be improved, the tact timefor transferring the device chips may be shortened, and themanufacturing cost may be reduced.

Furthermore, the first conveying table has the traversing device, whichallows the followings to be repeated:

after the device chips on the first substrate are made to be adhered tothe selective adhesive region of the third adhesive layer of the firstdrum,

the first drum is separated from the first substrate;

the first conveying table is moved using the traversing device; and

the device chips remaining on the first substrate are made to beselectively adhered to the selective adhesive region of the first drumwhere the device chips are not adhered.

This allows the intended device chips to be transferred from theselective adhesive region of the first drum to the second substrate.

Consequently, even if the second substrate area is larger than the firstsubstrate area, the device chips can be transferred from the first drumto the second substrate in a lump and the tact time for manufacturingthe electronic devices may be also shortened.

In the embodiment of the present invention, the apparatus formanufacturing electronic devices may further include a second drum.

The second drum may include a second rotation shaft, a second elevatingdevice for raising and lowering the second drum, a second rotationdevice for rotating the second drum around the second rotation shaft.

At least one of the first drum and the second drum may have a drum moverthat moves in a direction parallel to a longitudinal direction of thetraveling guide.

The first drum may include the third adhesive layer having the selectiveadhesive region.

The second drum may include a fourth adhesive layer, and an adhesionforce of the selective adhesive region may be weaker than an adhesionforce of the fourth adhesive layer.

In such above configuration, the device chips on the first adhesivelayer of the first substrate placed on the first conveying table is madeto be at least selectively adhered to the selective adhesive region ofthe third adhesive layer of the first drum,

the device chips are taken-out by moving the first conveying table whilethe first drum is being rotated,

subsequently, the first drum or the second drum is moved using the drummover,

the device chips adhered to the selective adhesive region of the thirdadhesive layer of the first drum are brought into contact with thefourth adhesive layer of the second drum, and

the device chips are transferred from the selective adhesive region ofthe first drum to the fourth adhesive layer of the second drum byrotating the first and second drums oppositely to each other.

In the above, since the adhesion force of the selective adhesive regionis weaker than the adhesion force of the fourth adhesive layer, thedevice chips may be surely transferred.

Subsequently, the first and second drums are separated each other,

the second drum is positioned on the second substrate placed on thesecond conveying table using the drum mover or using the secondtraveling device of the second conveying table,

the second elevating device lowers the second drum until the devicechips on the fourth adhesive layer of the second drum comes into contactwith the second adhesive layer of the second substrate,

the device chips on the fourth adhesive layer may be transferred to thesecond substrate by moving the second conveying table while the seconddrum is being rotated.

Consequently, the front and rear surfaces of each device chip can beinverted and the device chips may be surely transferred to the secondsubstrate, and thus, the arrangement accuracy for the device chips maybe improved and the tact time for transferring may also be shortened.

Additionally, since the first conveying table has the traversing device,it allows the following step to be repeated:

after the device chips on the first substrate are made to be adhered tothe selective adhesive region of the third adhesive layer of the firstdrum,

the first drum is separated from the first substrate;

the first conveying table is moved using the traversing device; and

the device chips remaining on the first substrate are made to beselectively adhered to the selective adhesive region of the first drumwhere the device chips are not adhered.

This allows the intended device chips to be transferred from theselective adhesive region of the first drum to the second substrate.

Consequently, even if the second substrate area is larger than the firstsubstrate area, the device chips may be transferred to the secondsubstrate in a lump while front and rear surfaces of each device chipare inverted between the first drum and the second drum, and the tacttime for manufacturing the electronic devices may be shortened.

In the embodiments of the present invention, the selective adhesiveregion may include convex portions.

The selective adhesive region of the first drum includes the convexportions, which are formed so to project from the surrounding adhesivelayer. This configuration allows the device chips to be selectivelyadhered to the predetermined area of the first drum. Additionally, thearrangement of the convex portions on the adhesive layer of the firstdrum are properly adjusted according to type of the electronic device,and it enables the intended number of the device chips to be adhered tothe intended area with intended positional accuracy.

The method and apparatus according to the embodiments of the presentinvention are used for transferring a variety of electronic devicechips, but not limited to light emitting elements, such as LEDs, toplace them in alignment on a substrate. Examples of the electronicdevice chips may include: a micro device chip, such as a light receivingelement, a piezo element, an acceleration sensor, NEMS, and MEMS; amemory element according to a charge storage system, or other systems,such as MRAM, FeRAM, and PCM; a switching element; and an operationprocessing device chip, such as a microcomputer.

Additionally, since the method according to the embodiments of thepresent invention does not include any heating process, a flexiblesubstrate or a substrate having relatively low heat resistance (equal toor less than 80° C.) may be also effectively used as a substrate usedfor transferring the device chips.

Furthermore, the electronic device manufactured using the methodaccording the embodiments of the present invention may be a part or thewhole of the product (final product) or may be a part or the whole ofthe intermediate product (object) or by-product.

Effects of the Invention

According to the embodiments of the present invention, the device chipsare selectively taken-out by making the selective adhesive region(convex portions) formed on the third adhesive layer of the first drumto come to line-contact with the device chips, and thus, pushing length(printing effect) during contacting can be reduced. Consequently,deterioration of positional accuracy, which is caused by an elasticdeformation or the like in the convex portions of the adhesive layerhaving elasticity, can be suppressed.

Additionally, the use of the first drum or the first and second drumsallows the device chips to be transferred from the first substrate tothe second substrate in a lump, and thus, the tact time formanufacturing the electronic devices may be shortened.

Furthermore, since the device chips can be at least selectivelytaken-out and can be placed on the position which is conformable withthe final product, the device chips can be more freely arranged.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of an apparatus for manufacturingelectronic devices according to a first embodiment of the presentinvention;

FIG. 2 is a perspective view of the apparatus for manufacturingelectronic devices according to the first embodiment of the presentinvention;

FIG. 3 is an enlarged view of a part of the apparatus for manufacturingelectronic devices where a first drum and a first substrate are incontact with each other according to the first embodiment of the presentinvention;

FIGS. 4A, 4B, 4C, and 4D are development diagrams illustratingarrangement examples of convex portions on a first drum;

FIG. 5 is a cross-sectional view of the apparatus in an operation stateaccording to the first embodiment of the present invention;

FIG. 6 is the other cross-sectional view of the apparatus in anoperation state according to the first embodiment of the presentinvention;

FIGS. 7A, 7B and 7C are plan views of the apparatus in an operationstate according to a second embodiment of the present invention;

FIGS. 8A, 8B and 8C are other plan views of the apparatus in anoperation state according to the second embodiment of the presentinvention;

FIGS. 9A and 9B are other plan views of the apparatus in an operationstate according to the second embodiment of the present invention; and

FIGS. 10A, 10B, and 10C are plan views of a transfer process of devicechips on the first substrate.

MODE FOR CARRYING OUT THE INVENTION First Embodiment

A first embodiment will be described below.

[Apparatus Configuration]

FIG. 1 is a cross-sectional view of an apparatus for manufacturingelectronic devices according to the first embodiment of the presentinvention.

A traveling guide 2 formed by a plurality of parallel rails, etc. isplaced on an apparatus base 1. Further, a first conveying table 3 and asecond conveying table 4 are mounted on the traveling guide 2, and thefirst conveying table can be moved using a first traveling device 5 andthe second conveying table 4 can be move using a second traveling device6 along the traveling guide 2.

The first conveying table 3 includes an alignment device 7 on the firsttraveling device 5 and further includes a traversing device 8 on thealignment device 7. The traversing device 8, the alignment device 7, andthe first traveling device 5 move along with the movement of the firstconveying table 3.

The traversing device 8 enables a first substrate 9 to move inlongitudinal and vertical directions of the traveling guide 2(H-direction shown in FIG. 2). The traversing device 8 further includesa first substrate supporting stand (not shown) where the first substrate9 may be mounted and held. The first substrate 9 includes a firstadhesive layer where a plurality of electronic device chips (hereinafterreferred as to “device chips”) 17 are adhered.

A use of the first substrate supporting stand prevents the positions ofthe first substrate 9 from being displaced on the traversing device 8when the first conveying table 3 is moved along the traveling guide 2 ormoved using the traversing device 8. Side faces or an upper face of thefirst substrate 9 may be mechanically pressed and held using the firstsubstrate supporting stand, or a back face of the first substrate 9 issucked using the first substrate supporting stand and the firstsubstrate 9 may be hold by the suction, but it is not limited to. Anydevice that can fix the position of the first substrate 9 may be used. Amethod for holding the first substrate 9 may be selected according tothe shape or behavior of the first substrate 9.

Examples of the device chip 17 may include: light emitting element, suchas LED: a micro device chip, such as a light receiving element, a piezoelement, an acceleration sensor, NEMS, and MEMS; a memory elementaccording to a charge storage system or other systems, such as MRAM,FeRAM, and PCM; a switching element; and an operation processing devicechip, such as a microcomputer, but not limited to.

The first substrate 9 includes the first adhesive layer and is formed bya flat substrate where a plurality of device chips are adhered. The flatsubstrate is manufactured using a silicon wafer, a compositesemiconductor wafer, a glass substrate, a substrate made of metallicoxide, such as sapphire, or the like, is often circular, and has from 4to 8 inches in diameter, but not limited to it. The first substrate 9itself may also be an adhesive substrate and may double as the firstadhesive layer. These device chips 17 are object to be transferred.

The alignment device 7 includes a mechanism for moving parallel to alongitudinal direction of the traveling guide 2 and the other mechanismfor rotating around a rotation shaft in a vertical direction that isperpendicular to the longitudinal direction (parallel to P-direction). Ause of the alignment device 7 also enables positions of the firstsubstrate 9 (reference position of the first substrate 9) to berecognized using optical means, etc. and enables the first substrate 9to be mounted (aligned) on a predetermined position with an accuracy ata spatial resolution of 0.1 μm and over a maximal moving distance ofseveral millimeters (e.g. 3 to 5 mm).

In addition to it, the above rotational mechanism also enables theangles to be adjusted to the longitudinal direction of the travelingguide 2 or a longitudinal direction of a first rotation shaft 15 of afirst drum (will be described below).

The second conveying table 4 includes an alignment device 20 on thesecond traveling device 6. The alignment device 20 includes a secondsubstrate supporting stand (not shown), and a second substrate 10(work), which the device chips 17 are to be transferred to, can bemounted on the second substrate supporting stand.

A use of the second substrate supporting stand prevents the positions ofthe second substrate 10 from being displaced when the second conveyingtable 4 is moved in a longitudinal direction of the traveling guide 2.The second substrate 10 includes a second adhesive layer, which isformed in portions where the device chips 17 are to be transferred.

The second substrate 10 may be not only a hard substrate made of glassor the like, but also a flexible substrate or the other substrate havinga low resistance to some process using heat, chemical, plasma, or theother treatment.

The alignment device 20 mounted on the second conveying table 4 providesthe same alignment precision as that of the alignment device 7.

The second substrate supporting stand may be a device to mechanicallypress and hold side faces or an upper face of the second substrate 10 ormay be the other device to suck a back face of the second substrate 10,but it is not limited to. Any device that can fix the position of thesecond substrate 10 may be used. A method for holding the secondsubstrate 10 may be selected according to the shape or behavior of thesecond substrate 10.

The second substrate 10 is a substrate for a display screen when thedevice chips 17 are LEDs, and the second substrate 10 is often largerthan the first substrate 9 as enlarged display screens are oftenmanufactured. The second substrate 10 is also not limited to a substratefor a display screen, and the second substrate 10 is an object where thedevice chips 17 are mounted, and becomes a different substrate dependingon the type of an electronic device to be manufactured or the type ofthe device chips.

As shown in FIG. 1, a first drum 11 (take-out barrel drum) and a seconddrum 12 (inversion barrel drum), which are circular cylindrical, arepositioned above the first conveying table 3 and the second conveyingtable 4.

The first drum 11 is cylindrical, and has a rotation shaft 15perpendicular to a longitudinal direction of the traveling guide 2 asshown in FIG. 2 and a rotation device (not shown) for rotating the firstdrum 11 around the rotation shaft 15. The rotation shaft 15 has liftingand lowering devices (not shown) at its both ends for moving the firstdrum 11 in P-direction in FIG. 1. The tilt of the rotation shaft 15 iscontrolled by independently driving each lifting and lowering device ina vertical direction and thus can be adjusted so as to be parallel to asurface of the first substrate 9.

Additionally, a supporting shaft vertically extending is provided at oneend of the rotation shaft 15 of the first drum 11, and the first drum 11includes a mechanism for vertically moving the first drum 11 along thesupporting shaft and for rotating the first drum 11 around the other endof the rotation shaft 15. The other end is positioned in horizontally tothe one end of the rotation shaft 15 at the supporting shaft. Themechanism allows an intersection angle (tilt) between the longitudinaldirection of the traveling guide 2 and the rotation shaft 15 to beadjusted, and it may be adjusted manually or using a linear motionmechanism.

The second drum 12 is cylindrical, and has a rotation shaft 16perpendicular to a longitudinal direction of the traveling guide 2 asshown in FIG. 2 and a rotation device (not shown) for rotating thesecond drum 12 around the rotation shaft 16. The rotation shaft 16 haslifting and lowering devices (not shown) at its both ends for moving thesecond drum 12 in P-direction in FIG. 1. The tilt of the rotation shaft16 is controlled by independently driving each lifting and loweringdevice in a vertical direction and thus can be adjusted so as to beparallel to a surface of the second substrate 10. In addition to thelifting and lowering device, a drum mover (not shown) for moving backand forth the second drum 12 parallel to the longitudinal direction ofthe traveling guide 2 is also provided.

Each rotation around the rotation shaft 15 of the first drum 11 andaround the rotation shaft 16 of the second drum 12 is driven using acombination of a direct drive motor and a rotation position detectionencoder, and the rotational angle is also detected using thecombination. The direct drive motor is directly connected to eachrotation shaft 15 and 16, and the rotation position detection encoderhas a higher resolution precision than a predetermined resolutionprecision.

As shown in FIG. 2, the rotation shaft 16 of the second drum 12 ispositioned so as to be parallel to the rotation shaft 15 of the firstdrum 11.

In one example, each diameter of the first drum 11 and the second drum12 being 100 to 500 mm is suitable to use in the viewpoint of machiningaccuracy, but not limited to the range.

A radius R₁ perpendicular to the rotation shaft 15 of the first drum 11and the other radius R₂ perpendicular to the rotation shaft 16 of thesecond drum 12 may be different each other. When the first and seconddrums having the same radius are brought into contact each other, theuniformity of the pressure of the contact area is easily assured.

As shown in FIGS. 2 and 3, a third adhesive layer 14 a having aselective adhesive region, and more particularly, convex portions 13, isprovided on a surface of the first drum 11, and the third adhesive layer14 a is made of silicone rubber or the like. A fourth adhesive layer 14b is provided also on a surface of the second drum 12, and the fourthadhesive layer 14 b is made of silicone rubber or the like. The firstand second adhesive layers may be made of the same type of resin.

The radius R₁ is a distance from the center of the rotation shaft 15 tothe convex portions 13, and the radius R₂ is a distance from the centerof the rotation shaft 16 to a surface of the fourth adhesive layer 14 b.When the device chips 17 are adhered to the convex portions 13 or thefourth adhesive layer 14 b, the above distance (R₁ or R₂) is a distancefrom the center of the rotation shaft 15 or 16 to surfaces of the devicechips 17, that is, one surface side of the device chips 17 where theadhesive layer is not contacted. In more detail, pushing length is givenwhen these drums are contacted, and thus, a basic definition for aradius:radius R ₁=(distance from the center of the first drum to the convexportions or the surfaces of the device chips)−(pushing length or itsone-half); andradius R ₂=(distance from the center of the second drum to the convexportions or the surfaces of the device chips)−(pushing length or itsone-half)

wherein “pushing length” is selected for a hard surface (high hardness)and “its one-half” is selected for an elastic body.

With a material for the convex portions of the first drum havinghardness differences, deformation quantity is increased at the moreelastic portion. When the device chips are adhered and separated usingthe drum, and more particularly, at the moment that the elasticdeformation of the drum is recovered when the separating is finished, arotational speed of the drum (peripheral speed or angular speed) getsfast and it may cause displacement at the same time.

The pushing length (printing effect) requires to be controlled forsuppressing the above variations. In one example, if the device chipsare arranged sparsely or densely by location, the printing effect isvaried and it causes the positional accuracy for transferring to bedeteriorated, and thus, the rotational speed of the drum (peripheralspeed or angular speed) requires to be controlled.

The convex portions 13 of the third adhesive layer 14 a can be formed byseparately preparing a plate (e.g. made of metal) with concave portionscorresponding to the convex portions 13, by pouring a photo-curableresin or a thermosetting resins onto the concavity plate, and by curingit. The photo-curable resin may be used for making the third adhesivelayer 14 a, and a lithography method may be also utilized. In oneexample, a thickness of the adhesive layer 14 a may be 5 to 500 μm, eachthickness of the convex portions 13 depends on the sizes of convexportions 13/the strength of the adhesive layer, and the convex portions13 project from the other portion of the third adhesive layer 14 a, forexample, by 5 to 250 μm, but not limited to.

Instead of configuring the selective adhesive region including theconvex portions 13 as described above, the selective adhesive region maybe made to have an adhesion force stronger than that of the otherportion on the third adhesive layer 14 a.

In one example, the third adhesive layer 14 a may be planarly formedusing some resins having adhesive properties, such as anultraviolet-curable resin, and the resins in the third adhesive layer 14a other than the selective adhesive region corresponding to thearrangement position of the device chips 17 that are subject to betaken-out may be cured by irradiation with ultraviolet rays, so as todecrease the adhesive force while the hardness of the resins areenhanced. For the above, “distance from the center of the first drum tothe convex portions or the surfaces of the device chips” in a formulafor computation of the radius R₁ is changed into “distance from thecenter of the first drum to the third adhesive layer 14 a or thesurfaces of the device chips.”

For a method for selectively irradiating ultraviolet rays, an exposureprocessing using a mask having an irradiation region for selectivelytransmitting or shielding ultraviolet rays may be employed, orultraviolet rays may be directly drawn. Thus, is it possible to producea selective adhesive region without producing the concavity plate.

Material of the adhesive layer may be an ultraviolet-curable resin or athermosetting resin. The resin for forming the third adhesive layer 14 aare not limited to the above, and the composition or the method is alsonot limited at all if the adhesive force of the resin in the area otherthan the selective adhesive region can be decreased according to thearrangement of the device chips 17. In this regard, the adhesive forceof between the device chips 17 and the area other than the selectiveadhesive region on the first adhesive layer is set to be weaker than theadhesive force between the device chips 17 and the selective adhesiveregion on the first adhesive layer.

Lifting and lowering devices allow the first drum 11 to be lowered untilthe convex portions 13 on the third adhesive layer 14 a of the firstdrum 11 comes into contact with the device chips 17 on the firstsubstrate 9, and the other lifting and lowering devices allow the seconddrum 12 to be lowered until the fourth adhesive layer 14 b of the seconddrum 12 comes into contact with the adhesive layer of the secondsubstrate 10. More precisely, the drum 2 is lowered until the devicechips 17 adhered to the fourth adhesive layer 14 b of the second drumcome into contact with the adhesive layer of the second substrate 10.

A resin having adhesive properties may be used for the third adhesivelayer 14 a and also for the fourth adhesive layer 14 b, and eachthickness is 5 to 500 μm in one example.

The first and second drums are lifted and lowed from a fiducial positionwhere outer peripheries of the first and second drums are parallel tothe surfaces of the first and second conveying tables. The centers ofthe rotation shafts of the first and second drums are assured to beorthogonal relative to a traveling axis of the traveling guide by meansof fiducial adjustment.

The alignment device 7 can detect a fiducial position of the first drum11 and can align the first substrate 9 and the first drum 11. Thealignment device 20 can detect a fiducial position of the second drum 12and can align the second substrate 10 and the second drum 12. Asdescribed above, the alignment can be performed with an accuracy at aspatial resolution of 0.1 μm and over a maximal moving distance ofseveral millimeters.

The convex portions 13 formed on the first drum 11 can be recognizedusing an optical apparatus, and the alignment device 7 of the firstconveying table 3 aligns the positions of the convex portions 13 and thepositions of each device chips on the first substrate 9. When thecurrent plate-like relay substrate is used, the device chips require tobe aligned on the flat surface of the plate-like relay substrate.However, a use of the relay substrate according to the embodiments ofthe present invention has only aligning the device chips substantiallyon a straight line and can also decrease applied pressures, and thus, itleads a deformation to be reduced and an alignment precision to beimproved.

The convex portions 13 are formed according to an arrangement pattern onthe first substrate 9 for the device chips. In one example, when thedevice chips are placed on the lattice points with a constant pitch, theconvex portions 13 are formed on a surface of the first drum 11 with thesame pitch as the constant pitch on the first substrate or with integralmultiples of the constant pitch.

As shown in FIG. 4A, the pitch is not necessarily constant, and thearrangement pattern of the convex portions 13 can be determined so as toselect the device chips 17 to be taken-out (picked up) according to thearrangement for transferring to the second substrate 10.

Each of FIGS. 4A to 4D is diagram where the adhesive layer of the firstdrum 11 is developed, wherein the X-direction in FIGS. 4A to 4D isparallel to the rotation shaft 15 of the first drum and Y-direction isvertical to the direction parallel to the rotation shaft 15 and is alonga circumference of the first drum 11.

The first conveying table 3 is moved in A-direction of one arrow in FIG.1 on the traveling guide 2 by the first traveling device 5 while keepinga horizontal level of the surface on the first substrate supportingstand.

The first substrate 9 an the first conveying table 3 move at the samespeed. The first drum 11 is synchronized with the first traveling device5, and can be rotated in B-direction of the other arrow in FIG. 1 by therotation device while keeping its position.

The rotation device of the first drum 11 and the first traveling device15 independently run and do not interfere with each behavior. This makeseasy to accurately keep a length between the first conveying table 3 andthe first drum 11 in a vertical direction (the shortest distance betweenthe rotation shaft 15 and the surface of the first substrate 9)constant.

[Transfer Process of Device Chips]

A method for manufacturing electronic devices using the above apparatusfor manufacturing electronic devices by transferring device chips fromthe first substrate 9 to the second substrate 10 will be describedbelow.

First, the first substrate includes the first adhesive layer, and thefirst adhesive layer where the plurality of device chips 17 are adheredis mounted on the first substrate supporting stand of the firstconveying table 3. After the first substrate 9 and the first drum 11 arealigned using the alignment device 7, the first drum 11 is positionedabove the first substrate 9.

Second, the first drum 11 is lowered, and the device chips 17 on thefirst substrate 9 and convex portions 13 of the third adhesive layer 14a are brought into contact.

However, the convex portions 13 does not necessarily come into contactwith the device chips 17 when the first drum 11 is lowered, and then,the convex portions 13 may come into contact with the device chips 17 byrotating the first drum and moving the first substrate as describedbelow.

FIG. 3 is an enlarged view of a part where the first drum 11 and thefirst substrate 9 are in contact with each other. The convex portions 13comes into contact with and adheres to the device chips 17 on anadhesive layer (not shown) of the first substrate 9.

The first conveying table 3 is moved in A-direction and the first drum11 is rotated in B-direction. This allows the device chips 17 to beseparated from the first substrate 9 and to be transferred to the firstdrum 11.

The rotating motion of the first drum 11 allows bringing the convexportions 13 into contact with the device chips 17 on the first substrate9 and separating the device chips 17 from the first substrate 9 to besequentially performed.

When the first drum 11 is rotated, a force directing obliquely upward bythe adhesive force of the convex portions 13 is applied on the devicechips 17 and the device chips 17 are separated from the surface of thefirst substrate 9. Then, the device chips 17 separated from the surfaceof the first substrate 9 are transferred to the convex portions 13formed in the third adhesive layer 14 a on the surface of the first drum11.

As described above, each device chip 17 is picked up sequentially froman end surface of the first substrate 9 during a separating process, andthus, a force for separating each device chip 17 can be reduced and italso leads to stably transferring the device chips 17 to the first drum11.

Although the convex portions 13 come into contact with the device chips17 on a flat surface when the conventional plate-like relay substrate isused, the apparatus using the relay substrate according to theembodiments of the present invention allows the convex portions 13 tocome into contact with the device chips 17 on a straight line parallelto the rotation shaft of the first drum 11. Consequently, a use of therelay substrate according to the embodiments of the present inventionallows less contact area between the convex portions 13 and the devicechips 17, allows applied pressures from the first drum 11 on the firstsubstrate 9 to be decreased, and also allows the uniformity of thepressure on the contact area to be improved, compared with theconventional plate-like relay substrate.

Furthermore, deformation over the adhesive layer 14 a having the convexportions 13 due to the pressure can be suppressed, and misalignment ofthe device chips 17 on the convex portions 13 can be reduced.

This effect occurs not only for the above, but also when the second drum12 is pressed against the second adhesive layer of the second substrate10 as will be described below, and the misalignment of the device chips17 on the second substrate 10 can also be suppressed.

In order to enable the device chips 17 to be transferred from the firstsubstrate 9 to the first drum 11, it is advantageous for the adhesiveforce between the convex portions 13 of the first drum 11 and the devicechips 17 to be stronger than that between the first adhesive layer ofthe first substrate 9 and the device chips 17.

For a method for adhering the device chips 17 to the first adhesivelayer of the first substrate 9, when LEDs are manufactured on a wafer inone example, known mounting techniques may be utilized: the wafer(semiconductor substrate) stuck on a dicing frame and diced may beutilized. (e.g. see JP 2003-318205 A1)

In this case, the dicing frame corresponds to the first substrate 9, aresin-made sheet of the dicing frame corresponds to the first adhesivelayer, and chips of the diced wafer respectively correspond the devicechips 17. Although commercial sheets whose adhesive force is known canbe used for the resin-made sheet of the dicing frame, an adhesive layerwhose adhesive force is adjusted may be formed on the resin-made sheet.It allows the adhesive force between the adhesive layer of the firstsubstrate 9 and the device chips 17 to be adjusted.

The above is a mere example, and examples of the device chips 17 are notlimited to the above and also include device chips other than LEDs. Amethod allowing the adhesive force to be provided according to kinds ofthe device chips and its manufacturing method is used, and thus, thefirst adhesive layer of the first substrate 9 can be adhered to thedevice chips 17.

Rotational speed (angular speed) of the first drum 11 is adjusted sothat each convex portion 13 of the first drum 11 respectively comes intocontact with each device chip 17 of the first substrate as shown in FIG.3.

In one example, “S” is given to a pitch of each convex portion 13, and“d” is given to a pitch of each device chip 17 of the first substrate 9.When the pitch of each convex portion 13 is equal to that of each devicechip 17, a speed of the first conveying table 3 in A-direction of anarrow in FIG. is “V_(A)”, and an angular speed of the first drum 11 is“ω”, the first drum 11 may be rotated at the angular speed whereω=ω₀=V_(A)/R₁: wherein R₁ is the radius of the first drum 11 asdescribed above. Although FIG. 3 shows one example where the pitches “S”and “d” are constant, that is, evenly spaced, the above relationalexpression depends on neither “S” nor “d”. The above relationalexpression is fulfilled even if the pitches are not evenly spaced, andthe pitches are not necessarily evenly spaced.

Additionally, the pitch “S” of each convex portion 13 and the pitch “d”of each device chip 17 of the first substrate 9 can also be relativelychanged by changing the angular speed “ω” from the above ω₀.

For example, when the angular speed “ω” of is changed into ω₁ differentfrom ω₀, it takes d/V_(A) to move the first substrate 9 by the pitch “d”and thus for the pitch “S” of each convex portion 13, S=R₁ω₁(d/V_(A)) isfulfilled. Accordingly, S/d=R₁ (ω₁/V_(A)), and the ratio of the pitch“S” to the pitch “d” is proportional to the angular speed “ω₁” of thefirst drum 11 and the moving speed “V_(A)” of the first conveying table3. Consequently, the pitch “S” of each convex portion 13 and the pitch“d” of each device chip 17 of the first substrate 9 can be madedifferent each other by changing the angular speed, and the differencebetween “S” and “d” may be varied by, for example, several tens of μm.The moving speed V_(A) may also be changed to the contrary.

When the ratio of the angular speed “ω₁” of the first drum 11 to themoving speed “V_(A)” of the first conveying table 3 is made to beconstant, the ratio of the pitches can be changed in the single uniformway. When the pitch “S” and/or the pitch “d” are not constant, theinformation about the position dependency is stored in a memory or thelike. The angular speed or the moving speed is then set according to theinformation, and the pitch “S” of each convex portion 13 may also beoptionally changed relative to the pitch “d” of each device chip 17 ofthe first substrate 9.

FIG. 4B is one example where the arrangement of each convex portion 13in FIG. 4A is changed. The arrangement can be changed in Y-axisdirection from that in FIG. 4A to that in FIG. 4B without changing thearrangement of the device chips 17 on the first substrate 9 by adjustingthe angular speed.

The first substrate 9 is moved in A-direction and perpendicular to theA-direction while the first drum 11 is being rotated, and the movingallows the arrangement of each convex portion 13 to be changed not onlyin A-direction but also perpendicular to the A-direction.

FIG. 4C is one example showing the above arrangement of each convexportion 13, and the arrangement is displaced (changed) in X-axisdirection. Each device chip 17 can be transferred to each convex portion13 whose arrangement is displaced (changed) without changing thearrangement of the device chips 17 on the first substrate 9 by movingthe first substrate 9 perpendicular to the A-direction. In this case, asshown in FIG. 4C, the pitches are not changed perpendicular to theA-direction of the convex portions 13, but

the position of each convex portion 13 is shifted in parallel.

The arrangement of each convex portion 13 is also displaced in both ofX-axis and Y-axis directions in FIG. 4D, but the device chips 17 can betransferred on the convex portions 13 without changing the arrangementof each device chip 17 on the first substrate 9 by moving the firstsubstrate 9 in A-direction and perpendicular to the A-direction and byadjusting the angular speed of the first drum 11.

As described above, the arrangement of each convex portion 13 is changedfrom that in FIG. 4A to those in FIGS. 4B, 4C, and 4D without changingthe arrangement of each device chip 17 on the first substrate 9, and thedevice chips 17 whose arrangement is equal to that of the convexportions 13 can be selected and adhered. Consequently, the arrangementof the device chips 17 on the second substrate can be changed asdescribed below. This allows a variety of electronic devices to bemanufactured. The variety of electronic devices cannot be manufacturedwithout changing the arrangement of the device chips 17 on the firstsubstrate 9 by using the conventional method using a flat relaysubstrate.

After the device chips 17 are transferred onto the convex portions 13 ofthe first drum 11, as shown in FIG. 5, the first drum 11 is raised andthe second drum 12 is then moved in a direction opposite to A-direction(C-direction) until the second drum 12 comes into contact with the firstdrum 11. Subsequently, the first drum 11 and the second drum 12 arerotated in the opposite directions each other (B-direction andD-direction). FIG. 5 shows that the first substrate 9 is not moved afterthe device chips 17 are transferred from the first drum 11. However, thefirst substrate 9 may be moved in a direction opposite to A-directionand returned to the original position (see FIG. 1).

Each angular speed of the first drum 11 and the second drum 12 isdetermined so that each speed in a tangent line direction of each radiusis the same at the contact position of the first drum 11 and the seconddrum 12. When “ω_(B)” is given to an angle around the rotation shaft 15of the first drum 11 and “ω_(C)” is given to an angle around therotation shaft 16 of the second drum 12, each rotational direction isopposite each other and thus each angular speed is set so as to fulfillω_(B)=−ω_(C) (R₂/R₁).

The applied forces on the first drum 11 and the second drum 12 are evenat the position where the first drum 11 comes into contact with thesecond drum 12, and thus, the above radius R₁ and radius R₂ arepreferably set to the same value and ω_(D)B=−ω_(C) is fulfilled.

The fourth adhesive layer 14 b of the second drum 12 includes resinhaving a stronger adhesive force than the adhesive layer 14 a of thefirst drum 11 includes. The stronger adhesive force allows the devicechips 17 of the first drum 11 to be separated from the convex portions13 included in the adhesive layer 14 a of the first drum and to betransferred to the fourth adhesive layer 14 b of the second drum. Thefourth adhesive layer 14 b, different from the third adhesive layer 14a, does not include the convex portions 13 (selective adhesive region),and uses the entire fourth adhesive layer 14 b to adhere to the devicechips 17.

As shown in FIG. 6, the second drum 12 is moved to a position above thesecond substrate 10 using the drum mover, and then, the second drum 12is lowered using the lifting and lowering device until the device chips17 adhered to the second drum 12 come into contact with the secondadhesive layer surface of the second substrate 10. Subsequently, whilethe second substrate 10 is moved in C-direction using the secondtraveling device 6 opposite to A-direction, the second drum 12 is beingrotated in D-direction.

Alternatively, the second drum 12 may be positioned above the secondsubstrate 10 by moving the second conveying table 4 using the secondtraveling device 6. In this configuration, if a relative positionalrelationship between the second drum 12 and the second substrate 10 canbe established, whichever may be moved.

The angular speed of the second drum 12 is set so that the speed in atangent line direction of the device chips 17 adhered to the second drum12 that comes into contact with the second substrate 10 equals to aspeed of the second substrate 10 moving in C-direction, and the seconddrum 12 is rotated in D-direction. In one example, when V_(D) is givento the moving speed in C-direction of the second substrate 10, the aboveradius of the second drum 12 is R₂ and the angular speed of the seconddrum 12 may be set to V_(D)/R₂.

The angular speed of the second drum 12 may be set to a differentangular speed from that of the above second drum 12 like a relationshipbetween the angular speed of the first drum 11 and the moving speed ofthe first substrate 9, but the device chips 17 adhered to the seconddrum 12 have been already position-adjusted and aligned, and thus, theangular speed of the second drum 12 may be generally set to the angularspeed of the above relationship.

Although the moving direction of the second substrate 10 representsC-direction in the above embodiment, the second substrate 10 may bemoved in A-direction and the second drum 12 may be rotated in adirection opposite to D-direction. The relative positional relationshipbetween the second drum 12 and the second substrate 10 is established,and thus, the rotational direction of the second drum 12 may bedetermined by matching with the moving direction of the second substrate10. This may be also satisfied in the relationship between the firstdrum 11 and the first substrate 9, and it is not limited to the movingdirection in each above embodiment.

Alternatively, the device chips 17 may be transferred to the secondsubstrate 10 by moving the second drum 12 in parallel in A-directionwhile the second drum 12 is rotated in D-direction. However, therotation device of the second drum 12 is operated independently of thesecond traveling device 6 to make the second substrate 10 move inparallel in a horizontal direction, and it does not cause each operationto be interfered and easily makes the distance in the vertical directionbetween the second drum 12 and the second substrate 10 to accuratelykept constant.

As described above, the device chips 17 are transferred from the firstsubstrate 9 to the second substrate 10 through the convex portions 13 ofthe first drum 11 and the second drum 12. It means that the arrangementof the device chips 17 on the second substrate 10 depends on thearrangement of the convex portions 13. The arrangement of the convexportions 13 can be adjusted as described above, and for example, thepitch of the device chips 17 may be widened or narrowed at the centerportion of the second substrate 10.

Although the embodiment that the second drum 12 is brought into contactwith the first drum 11 by parallel moving the second drum 12 to transferthe device chips 17 from the first drum 11 to the second drum 12 isdescribed, the first drum 11 may include a drum mover and may be broughtinto contact with the second drum 12 by parallel moving the first drum11 using the moving device.

In this way, the device chips 17 may be transferred from the second drum12 to the second substrate 10 in a lump, and it may greatly reduce thetact time.

Additionally, the device chips 17 adhered to the convex portions 13 ofthe first drum 11 may be directly transferred onto the second substrate10 without using the second drum 12 so that the front-and-rear relationfor the surfaces of each device chip 17 on the second substrate 10 ismade same to that of the device chip 17 on the first substrate 9. Inthis case, the first drum 11 may also include a drum mover.

When the second drum 12 is not used, it is understandable that thedevice chips 17 may be transferred onto the second substrate 10 by usingthe first drum 11 instead of the second drum 12 in the abovedescription, and thus, the details are omitted.

Additionally, using the first drum 11 and the second drum 12 ondifferent occasions, combining one transfer of only the first drum 11with the other transfer of both of the first drum 11 and the second drum12 and using them properly to transfer the device chips 17 allow thearrangement of each device chip 17 with different front-and-rearrelations for the surfaces to selectively formed in a lump.

For example, the device chips 17 whose front-and-rear relation for thesurfaces is inversed through the first drum 11 may be adhered from thefirst substrate 9 onto the second drum 12, then, the adhesive layer 14 ahaving the convex portions 13 with a different type of arrangement maybe attached to the first drum 11, the device chips 17 may be adheredfrom the first substrate 9 onto the convex portions 13 whosefront-and-rear relation for the surfaces is not inversed of the firstdrum 11, and the device chips 17 may be sequentially transferred fromthe first drum 11 to the second substrate 10 and from the second drum 12to the second substrate 10, or the device chips 17 may be alsosequentially transferred in the opposite way.

Alternatively, the device chips 17 may be transferred from the firstsubstrate 9 to the second substrate 10 through the first drum 11, then,the adhesive layer 14 a having the convex portions 13 with a differenttype of arrangement may be attached to the first drum 11, and the devicechips 17 may be transferred from the first substrate 9 to the secondsubstrate 10 through the first drum 11 and the second drum 12, or thedevice chips 17 may be also transferred in the opposite way.

It may be determined whether the second drum 12 are necessary or not bycomparing the mounting situations of the device chips 17 between thesecond substrate 10 and the first substrate 9. Examples are describedbelow to easily make determination whether the second drum 12 arenecessary or not, but it is not limited to.

For example, after the device chips 17 are transferred to the secondsubstrate 10, the device chips 17 may be selected depending to aformation method of an electric wiring between electric terminals, suchas a connection terminal for power and a connection terminal forelectric signals, of the device chips 17 and electrical connectionterminals of the other circuit on the second substrate 10.

In one example, when the device chips 17 are LEDs, when the lightemitting surfaces are on an upper side (upper surface) of the firstsubstrate 9, and when the LEDs include electric power supply terminalson the opposing surfaces, the front-and-rear relation for the surfacesof the LEDs may be inversed using the second drum 12, the surfaces withthe electric power supply terminals of the LEDs may be positioned facingupward, then, conductive wiring may be formed, and the LEDs may beelectrically connected to a switching circuit or the like positioned onthe second substrate 10.

In the other example, when the device chips 17 are memory elements andelectrical connection terminals, such as a connection terminal for powerand a connection terminal for electric signals, are on the upper side ofthe first substrate 9, the memory elements may be transferred from thefirst drum 11 to the second substrate 10 without inversing thefront-and-rear relation for the surfaces of the memory elements andwithout using the second drum 12.

The relationship of the adhesive forces against the device chips 17, asalready described, is necessary to transfer the device chips 17 from thefirst substrate 9 to the first drum, to the second drum 12, and to thesecond substrate 10 sequentially as described above, wherein:

the adhesive force is getting stronger in the order of (adhesive forceof the first adhesive layer of the first substrate 9)<(adhesive force ofthe selective adhesive region on the third adhesive layer 14 a of thefirst drum)<(adhesive force of the fourth adhesive layer 14 b of thesecond drum 12)<(adhesive force of the second adhesive layer of thesecond substrate 10). However, the second drum 12 may be notoccasionally used. As described above, the selective adhesive regioncorresponds to the convex portions 13.

The adhesive force of the adhesive layer may be controlled by adjustingthe blending ratios of materials for the adhesive layer.

The material of the adhesive layer may be selected from at least one ormore combination selected from examples of known adhesive agentsincluding acrylic-based adhesive, rubber-based adhesive, vinyl alkylether-based adhesive, silicone-based adhesive, polyester-based adhesive,polyamide-based adhesive, urethane-based adhesive, fluorine-basedadhesive, epoxy-based adhesive, and polyether-based adhesive, but notlimited to.

Additionally, the material of the adhesive layer may properly includeone or more additive substance selected from examples of conditioner forviscosity and separation degree, tackifier agent, plasticizer, softener,filler (including fibrous glass, glass beads, metal powders, and theother inorganic powder, etc.), coloring agent (pigment and dye, etc.),and additive agent (pH adjuster, antioxidant, and ultraviolet absorber,etc.).

Table 1 shows examples of a result that blending of materialcompositions for the adhesive layer is changed and that the adhesiveforce and hardness are examined. As shown in Table 1, change of theblending can change the adhesive force. In addition to it, change of theblending can also change the hardness.

The hardness was measured according to JIS K 6253, and the adhesiveforce was measured according to JIS 0237.

TABLE 1 Adhesive Blending force [kg/cm²] Hardness [°] A 0.36 60.0 B 0.4643.0 C 0.73 27.7 D 0.83 42.7 E 0.92 35.3 F 0.74 14.7 G 0.85 16.7

When the adhesive layers are contacted each other, a resin having lowhardness causes a deformation and deteriorates the placement accuracy ofthe device chips 17, and thus, a certain amount of hardness isnecessary. A resin having high hardness tends to weaken the adhesiveforce, and thus, it should be carefully considered what type of resin isused also from the aspect of the adhesive force. When silicone-basedresin is used in Table 1, for example, resin having desirable hardnesscan be selected preferably in a range of hardness 30 to 60.

In one example, “blending A” for the first adhesive layer of the firstsubstrate 9, “blending B” for the third adhesive layer of the first drum11, “blending D” for the fourth adhesive layer of the second drum 12,and “blending E” for the second adhesive layer of the second substrate10 may be selected from combinations of the above adhesive force amongthe resins listed in Table 1.

Although thickness of each adhesive layer may be optionally set in theabove range for example, preferably 5 to 100 μm, and more preferably 10to 60 μm.

When the thickness of the adhesive layer is less than 5 μm, the adhesiontends to be lowered and a major change in ambient temperature maydeteriorate its durability.

In one example, when an adhesive material is used for the first drum 11including the adhesive layer whose thickness is less than 5 μm havingthe convex portions 13,

(1) the convex portions 13 are formed on the position where the devicechips 17 intended to taken-out are positioned, but the adhesive layermay be adhered to the device chips 17 that are not intended to taken-out(it depends on the pushing length),

(2) when a primer layer or the like requires to be formed as a baseduring forming the adhesive layer, composition/performance of theadhesive layer may suffer effects from an infiltration of the primerlayer,

(3) if a thickness of a viscoelastic body layer configuring the adhesivelayer is too thin, recess in a thickness direction (dispersion ofstresses) cannot be ensured, and thus, the pushing stresses may beincreased and it may cause the device chips 17 to be damaged or maydeform the convex portions 13, and

(4) the limit of accuracy of the apparatus is concerned.

Additionally, when the second drum 12 is used, the above (2), (3), and(4) are concerned.

On the other hand, when a thickness of the adhesive layer is more than100 μm, some problems, such as air bubbles remained when the compositionfor the adhesive material is coated and dried and ununiformity inthickness over the adhesive layer surface, may cause an adhesiveness tobe deteriorated.

In the other example, when an adhesive material is used for the firstdrum 11 including the adhesive layer whose thickness is more than 100 μmhaving the convex portions 13,

(1) if a thickness of the adhesive layer is too thick a reaction forceagainst pushing is decreased, imprinting required to take-out the devicechips 17 is also decreased, it may cause failing to taking out thedevice chips 17, and thus, the pushing length requires to be ensuredlong,

(2) furthermore, if the pushing length is ensured long, it may increasethe deformation quantity and may deteriorate a positional accuracy forthe device chips 17.

Additionally, since a height of each convex portion 13 is related to aground area, the aspect ratio is preferably equal to or less than 4. Thepositional accuracy for the device chips 17 is affected by thedeformation or the like of the convex portions 13.

Considering the positional accuracy, preferably for the form of eachconvex portion 13, the height is 5 to 60 μm, the aspect ratio is equalto or less than 4, and the lateral sides are not vertical and the taperangles are 20 to 80 degrees. If an especially high positional accuracy(e.g. single micrometer order) desires to be achieved, preferably forthe best form of each convex portion 13, the height is 10 to 40 μm, theaspect ratio is 2 to 3, and the taper angles of the lateral sides are 30to 60 degrees.

The form of each convex portion 13 is properly selected from the aboverange in consideration of shapes or physical properties (hardness,surface state, or the like), etc. of the device chips that are subjectto be transferred also other than the positional accuracy.

As described above, for the selective adhesive region, the arrangementof the convex portions 13 may not only determine the arrangementportions for the device chips, but also may optimize the configurationof the selective adhesive region so as to adapt to the device chips.

Furthermore, during a process for forming the adhesive layer, a thickadhesive layer typically may cause “sink” due to the shrinkage of aresin when cured (volumetric shrinkage), its shape stability may belowered, a risk that air bubbles mix into the adhesive layer may beincreased, and they may be problems.

In one example, a vacuum agitation technology may be used when thematerial is mixed to prevent air bubbles or the like, and an influxproperty of the material against the matrix (concave plate) iscontrolled based on the contact angles with interface.

However, a thin adhesive layer may cause cissing/deviation due to thesurface tension. If a primer layer is formed to ensure adhesion, theprimer layer may affect the composition of the adhesive layer by leadingto, for example, diffluence and infiltration.

Additionally, the device chips 17 may be firmly fixed by forming UVcuring resin or the like on the device chip 17 and the second substrate10 after the device chips 17 are positioned on the second substrate 10.

Second Embodiment

A second embodiment will be described below.

In one example, when LEDs are transferred, a circular wafer used for asemiconductor process is used for manufacturing device chips to beadhered to the first substrate 9. When the wafer is made of siliconsingle crystalline, the wafer of 4 to 8 inch or 12 inch at the maximumis often used. When the wafer is made of group III-V compoundsemiconductor, the wafer of 3 to 4 inch is often used. The size of thefirst substrate 9 is determined according to the size of the wafer. Onthe other hand, the second substrate 10 may be a display apparatus witha large screen (e.g. diagonal length is 50 inch).

Even if the size of the first substrate 9 is greatly different from thesize of the second substrate 10, and particularly even if the size(width) of the second substrate 10 is larger than the size of the firstsubstrate 9, the embodiments of the present invention can effectivelywork.

As shown FIG. 7B, L is a length in a direction of the rotation shaft 15and is the length of an area in the first drum 11 where the convexportions 13 are formed, and, as shown in FIG. 7A, W is a width (lengthin a direction parallel to the rotation shaft 15) of the secondsubstrate 10 where the device chips 17 are to be transferred. The lengthL is set to equal to or greater than the width W.

As shown in FIGS. 7B and 7C, one end of the convex portions 13 in thefirst drum 11, that is, one right end (dotted line cc) is aligned withthe other right end (dotted line β) of a separating area where some ofthe device chips 17 formed on the first substrate 9 are positioned to beseparated for being transferred. In other words, the first substrate 9is moved in A-direction, and is position-adjusted so as to adhere to oneend of the convex portions 13 when the first drum 11 is rotated.

The traversing device 8 enables the first substrate 9 in longitudinaland parallel directions of the rotation shaft 15 of the first drum 11,and thus, the first substrate 9 can be position-adjusted.

The above physical relationship between the convex portions 13 and thefirst substrate 9 (dotted lines α and β) is a mere example, and thephysical relationship may be properly defined according to thearrangement of the convex portions 13 and the first substrate 9, theform of each convex portion 13, and the shapes of the device chips 17.It allows the convex portions 13 to take-out the device chips 17positioned in the predetermined area.

The form of each convex portion 13 may be changed according to, forexample, the shape of each device chip 17, they may be the same, andexamples of the form and shape includes circular, oval, and rectangular.The area in the convex portions 13 where one device chip 17 correspondmay be formed either by one convex portion 13 or by the plurality ofconvex portions 13. The contact surface of the convex portion 13 may belarger or narrower than that of the device chip 17. For example, whenthe contact surface of the convex portion 13 is narrower than that ofthe device chip 17, the dotted line β may be shifted to left side inFIG. 7C, and when the contact surface of the convex portion 13 is largerthan that of the device chip 17, the dotted line β may be shifted toright side in FIG. 7C.

Subsequently, the convex portions 13 of the first drum 11 is lowereduntil the convex portions 13 comes into contact with the surfaces of thedevice chips 17 on the first substrate 9. While the first substrate 9 ismoved in A-direction, the first drum 11 is rotated and the device chips17 on the first substrate 9 is made to be selectively adhered to theconvex portions 13. The relationship between the rotational speed of thefirst drum 11 and the moving speed and direction of the first substrate9 are as described in the first embodiment of the present invention.

As shown in FIGS. 8A, 8B and 8C, the first drum 11 is raised, and thefirst substrate 9 is returned to the original position where the firstsubstrate 9 was positioned before the adhering of the device chips 17was started. The first substrate 9 is then moved in E-direction (thatis, parallel to a longitudinal direction of the rotation shaft 15 of thefirst drum 11) by a distance corresponding to a width of an area(separate-area 19) where the device chips 17 to be separated from thefirst substrate 9 are positioned, and the E-direction is a directiontoward the area in the convex portions 13 of the first drum 11 where thedevice chips 17 have not been adhered. As described below, the firstsubstrate 9 is moved further by a distance (pitch) so as to allowing thedevice chips 17 to be transferred, and the first drum 11 is rotated to aposition where the convex portions 13 where the device chips 17 have notbeen adhered are allowed to start transferring the next device chips 17.

Subsequently, the above process, the separating of the device chips 17using the first drum 11, the rotating of the first drum 11, and themoving of the first substrate 9 (see FIGS. 8A, 8B and 8C) are repeated,and as shown in FIGS. 9A and 9B, the device chips 17 are made to beadhered to the area where all the convex portions 13 of the first drum11 are positioned or the area where the convex portions 13 intended tobe transferred to the second substrate 19 are positioned.

For transferring the device chips 17 to the plurality kinds of thesecond substrates 10 for product having different sizes, the first drum11 having the convex portions 13 corresponding to the product, which isconsidered to be the largest, may be prepared. Subsequently, a partialarea of the above convex portions 13 of the drum 11 may be also used forsmaller sized product. This allows the third adhesive layer 14 a of thesingle first drum 11 to be used to produce a plurality kinds ofelectronic device products.

Subsequently, in the same way as in the first embodiment, the devicechips 17 adhered to the convex portions 13 of the first drum 11 aretransferred to the second drum 12, and the device chips 17 adhered tothe second drum 12 are transferred onto the second substrate 10.

As described in the first embodiment, the device chips 17 may betransferred from the first drum 11 to the second substrate 10 withoutusing the second drum 12.

Additionally, the device chips 17 including a different front-and-rearrelation for the surfaces may be properly transferred by combining oneprocess of transferring the device chips 17 using only the first drum 11with the other process of transferring the device chips 17 using both ofthe first drum 11 and the second drum 12.

According to the above embodiment of the present invention, the devicechips 17 may be transferred multiple times from the first substrate 9 tothe first drum 11. In a first transferring process, the device chip 17is transferred from the first substrate 9 to the first drum 11, and theabove device chip 17 transferred disappear on the first substrate 9after the above transferring. In the next transferring process, in orderto transfer the device chip 17 from the first substrate 9 to the firstdrum 11, the first substrate 9 will be position-adjusted and shifted byone pitch for the device chips 17 on the first substrate 9 in oneexample.

With reference to FIGS. 10A to 10C, a positional adjustment of the firstsubstrate 9 required for transferring the device chips 17 multiple timeswill be described below. Each device chip 17 is assumed to be positionedon each intersection of an equal-distance grid to simplify thedescription. FIGS. 10A to 10C are plan views of a transferring processof the device chips 17 on the first substrate 9: wherein “X-axis” isgiven to one direction parallel to A-direction and “Y-axis” is given tothe other direction perpendicular to A-direction.

As shown in FIG. 10A, m pieces of device chips 17 in X-direction and npieces of device chips 17 are assumed as one unit. Both of “m” and “n”are positive integers, and one of them is an integer larger than one.One unit includes m×n pieces of device chips 17. When the device chips17 are transferred from the first substrate 9 to the first drum 11 onlyonce, both of m and n may also be one.

As shown in FIG. 10B, for a first transferring process, one device chip17 is transferred from each unit, that is, from the first substrate 9 tothe first drum 11.

As shown FIG. 10C, for a second transferring process, after the firstsubstrate 9 is moved by a distance corresponding to a width of theseparating area 19, the first substrate 9 is moved by one pitch for thedevice chips 17 in X- or Y-direction, and the device chip 17 (in eachunit) is transferred from the first substrate 9 to the first drum 11.FIG. 10C shows one example where the device the device chip 17 istransferred after the first substrate 9 is moved by one pitch inX-direction.

Likewise, the device chip 17 may be transferred one by one from eachunit including m×n pieces of device chips 17 to the first drum 11.

Additionally, although the first substrate 9 is moved in X-direction inFIGS. 10A to 10C, the first substrate 9 may be moved in X-direction ormay be moved by one pitch in both of X- and Y-directions. If the firstsubstrate 9 is moved within the unit including m×n pieces of the devicechips 17, the first substrate 9 may be moved by more than one pitch andthe device chips 17 positioned in the intended area may be properlytransferred.

One example that the device chips 17 are arranged on the equal-distancegrid is described above, but for the device chips 17 arranged accordingto a predetermined rule, the plurality of device chips 17 may configuredto be one unit. Consequently, a plurality of repetitions of transferringfrom the first substrate 9 to the first drum 11 enable the intendednumber of the device chips 17 to be transferred (adhered). The intendednumber means the number of device chips 17 intended to be transferred tothe second substrate 10.

Additionally, one example of a systematic method (process) is describedabove for transferring the device chips 17 multiple times, but it is notlimited to. The first substrate 9 may be also properly moved fortransferring the device chips 17 multiple times.

For transferring more device chips 17 to the convex portions 13, theplurality of first substrates 9 may be also prepared and properlyreplaced. Different kinds of device chips 17 are adhered to each firstsubstrate 9, the different kinds of device chips 17 may be transferredfrom to the single first drum 11 using the plurality of first substrates9.

Even in this case, the device chips 17 may be transferred to alarge-screen display apparatus, and also the transferring from the firstdrum 11 to the second drum 12 or transferring from the second drum 12 tothe second substrate 10 may be performed in a lump. This may shorten thetact time, and thus, may also reduce the manufacturing cost.

REFERENCE SIGNS LIST

-   1. apparatus base-   2. traveling guide-   3. first conveying table-   4. second conveying table-   5. first traveling device-   6. second traveling device-   7. alignment device-   8. traversing device-   9. first substrate-   10. second substrate-   11. first drum-   12. second drum-   13. convex portions-   14 a. third adhesive layer-   14 b. fourth adhesive layer-   15. rotation shaft-   16. rotation shaft-   17. device chip-   18. transfer-area-   19. separate-area-   20. alignment device

The invention claimed is:
 1. A method of manufacturing electronicdevices comprising: a preparation step for preparing a first substratehaving a first adhesive layer and a second substrate having a secondadhesive layer, the first adhesive layer including a surface where aplurality of device chips are adhered; a first take-out step for makingat least part of the device chips on the first substrate come intocontact with and adhere to at least part of a selective adhesive regionon a third adhesive layer of a first drum and for separating the atleast part of the device chips from the first substrate by rotating thefirst drum; and a first transfer step for making the device chips on theselective adhesive region come into contact with and adhere to thesecond adhesive layer and for separating the device chips from theselective adhesive region by rotating the first drum.
 2. The method ofmanufacturing electronic devices according to claim 1, wherein anadhesion force between the first adhesive layer and the device chips isweaker than an adhesion force between the selective adhesive region andthe device chips, and wherein the adhesion force between the selectiveadhesive region and the device chips is weaker than an adhesion forcebetween the second adhesive layer and the device chips.
 3. A method ofmanufacturing electronic devices comprising: a preparation step forpreparing a first substrate having a first adhesive layer and a secondsubstrate having a second adhesive layer, the first adhesive layerincluding a surface where a plurality of device chips are adhered; afirst take-out step for making at least part of the device chips on thefirst substrate come into contact with and adhere to at least part of aselective adhesive region on a third adhesive layer of a first drum andfor separating the at least part of the device chips from the firstsubstrate by rotating the first drum; an inversion step for making thedevice chips on the selective adhesive region of the first drum comeinto contact with and adhere to a fourth adhesive layer of a second drumand for separating the device chips from the selective adhesive regionby rotating the first drum and the second drum oppositely to each other;and a second transfer step for making the device chips come into contactwith and adhere to the second adhesive layer and for separating thedevice chips from the second drum by rotating the second drum.
 4. Themethod of manufacturing electronic devices according to claim 3, whereinan adhesion force between the first adhesive layer and the device chipsis weaker than an adhesion force between the selective adhesive regionand the device chips, wherein the adhesion force between the selectiveadhesive region and the device chips is weaker than an adhesion forcebetween the fourth adhesive layer and the device chips, and wherein theadhesion force between the fourth adhesive layer and the device chips isweaker than an adhesion force between the second adhesive layer and thedevice chips.
 5. A method of manufacturing electronic devices,comprising: a preparation step for preparing a first substrate having afirst adhesive layer and a second substrate having a second adhesivelayer, the first adhesive layer including a surface where a plurality ofdevice chips are adhered; and a first transfer process and a secondtransfer process; wherein: the first transfer process comprises: a firsttake-out step for making at least part of the device chips on the firstsubstrate come into contact with and adhere to at least part of aselective adhesive region on a third adhesive layer of a first drum andfor separating the at least part of the device chips from the firstsubstrate by rotating the first drum; and a first transfer step formaking the device chips on the selective adhesive region come intocontact with and adhere to the second adhesive layer and for separatingthe device chips from the selective adhesive region by rotating thefirst drum; and the second transfer process comprises: a second take-outstep for making at least part of the device chips on the first substratecome into contact with and adhere to at least part of a selectiveadhesive region on a third adhesive layer of a first drum and forseparating the at least part of the device chips from the firstsubstrate by rotating the first drum; and an inversion step for makingthe device chips on the selective adhesive region of the first drum comeinto contact with and adhere to a fourth adhesive layer of a second drumand for separating the device chips from the selective adhesive regionby rotating the first drum and the second drum oppositely to each other;and a second transfer step for making the device chips come into contactwith and adhere to the second adhesive layer and for separating thedevice chips from the second drum by rotating the second drum.
 6. Themethod of manufacturing electronic devices according to claim 1,comprising: the first take-out step; and further a parallel-move stepfor separating the first drum from the first substrate after the firsttake-out step and for moving the first substrate in a direction parallelto a rotation shaft of the first drum, wherein the first take-out stepand the parallel moving step are repeated several times, so as totransfer the device chips to the selective adhesive region of the firstdrum.
 7. The method of manufacturing electronic devices according toclaim 1, wherein the selective adhesive region comprises convexportions.
 8. An apparatus for manufacturing electronic devicescomprising: a traveling guide; a first conveying table; a secondconveying table; and a first drum, wherein the first conveying tableincludes: a first traveling device that makes the first conveying tablemove on the traveling guide; and a traversing device that movesperpendicularly to a longitudinal direction of the traveling guide,wherein the second conveying table includes a second traveling devicethat makes the second conveying table move on the traveling guide, andwherein the first drum includes: a first rotation shaft; a firstelevating device for raising and lowering the first drum; a firstrotation device for rotating the first drum around the first rotationshaft; and a mechanism for controlling a tilt angle of the firstrotation shaft in a direction parallel to a first directionperpendicular to the first conveying table and a direction parallel to asecond direction parallel to the first conveying table, and furtherincludes a third adhesive layer having a selective adhesive region. 9.The apparatus for manufacturing electronic devices according to claim 8,further comprising a second drum, wherein the second drum includes: asecond rotation shaft; a second elevating device for raising andlowering the second drum; and a second rotation device for rotating thesecond drum around the second rotation shaft, wherein at least one ofthe first drum and the second drum has a drum mover, and the drum movermoves in a direction parallel to a longitudinal direction of thetraveling guide, and wherein the second drum includes a fourth adhesivelayer, and an adhesion force of the selective adhesive region is weakerthan an adhesion force of the fourth adhesive layer.
 10. The apparatusfor manufacturing electronic devices according to claim 8, wherein theselective adhesive region comprises convex portions.